Quotation vs Invoice vs Proforma Invoice: What's the Difference?
Three documents that look alike, printed on similar templates, often confused with each other — yet each has a completely different commercial and tax meaning. Here is the clearest way to keep them straight.
The one-line answer
A quotation is an offer made before the customer agrees. A proforma invoice is a preview sent after agreement but before supply. A tax invoice is the real thing, issued at the time of supply, and it is the only one of the three that matters for GST.
The quotation: your opening offer
A quotation is a commercial proposal. It lists what you can supply, at what price, with what taxes, and on what conditions. Nothing is owed at the quotation stage — the customer may negotiate, accept only some lines, or walk away entirely. Because prices of raw materials change, a quotation should always carry a validity period (15–30 days is typical) so you are not held to old prices months later.
A quotation lives or dies on clarity. Itemise every product or service on its own line with its own price and GST rate, show the discount separately if you are giving one, and include your bank details so an accepting customer can pay an advance without another phone call. You can create exactly this format — logo, itemised GST table, bank details, terms and authorised-signatory block — with our free Quotation Maker.
The proforma invoice: the preview
A proforma invoice sits between quotation and tax invoice. It is usually issued when the deal is essentially agreed but the supply has not yet happened — for example, when the buyer needs a document to raise a purchase order internally, arrange a bank loan or letter of credit, or release an advance payment. It looks almost identical to a tax invoice (same table, same totals) but is clearly titled "Proforma Invoice".
Crucially, a proforma invoice is not a GST document. It creates no tax liability, is not reported in GSTR-1, and the buyer cannot claim input tax credit against it. Think of it as a formal preview of the invoice to come.
The tax invoice: the real document
The tax invoice is issued when the supply actually happens (or within the time limits GST law prescribes for goods and services). It must carry the mandatory fields set out in the GST invoice rules — consecutive serial number, date, GSTINs, place of supply, HSN/SAC, taxable value, tax rate and amount, and so on. It is the document that flows into your GSTR-1, generates the buyer's input tax credit, and — above the applicable turnover threshold — needs an IRN under e-invoicing. See our full guide to GST invoice rules and mandatory fields, or build one now with the GST Invoice Generator.
Side-by-side comparison
| Quotation | Proforma Invoice | Tax Invoice | |
|---|---|---|---|
| When sent | Before the customer agrees | After agreement, before supply | At the time of supply |
| Purpose | Offer prices & terms | Preview the final bill; enable PO, advance or funding | Demand payment; record the taxable supply |
| Binding? | No — an offer, open to negotiation | No — informational | Yes — records an actual transaction |
| GST effect | None | None | Creates GST liability; enables buyer's ITC |
| Appears in returns? | No | No | Yes — GSTR-1 |
| Numbering | Any internal series (QTN-001…) | Any internal series | Consecutive serial, unique for the financial year |
| Can prices change after? | Yes, until accepted / validity expires | Usually final, minor changes possible | No — changes need a credit/debit note |
A typical order flow
- Enquiry → Quotation. The customer asks for prices; you send a quotation with a 30-day validity. Negotiation happens here.
- Acceptance → Proforma (optional). The customer agrees; if they need a document for an advance or a purchase order, you send a proforma invoice for the agreed amount.
- Supply → Tax invoice. You deliver the goods or complete the service and issue the tax invoice with a proper serial number. This is the document with GST consequences.
- Changes → Credit/debit note. If a price or quantity changes after invoicing, you adjust with a credit or debit note — never by editing the issued invoice.
Common mistakes to avoid
Titling a proforma as "Invoice". If the document is not a tax invoice, say so plainly in the title — otherwise the buyer's accounts team may book it, and reconciliation problems follow.
Skipping the validity date on quotations. Without it, a customer can return after six months and insist on old prices. One line prevents the argument.
Reusing the invoice serial for quotations. Your tax invoice series must be clean and consecutive for GST; mixing quotation numbers into it creates gaps that are painful to explain.
Treating an accepted quotation as the bill. Acceptance closes the negotiation, but you must still raise a tax invoice at supply — that is what your GST return and the customer's input credit depend on.